I think this problem is not limited to x64, but affects all 64bit
platforms, so
we may need to think about a way to push/hoist the ChangeUint32ToUint64
operations up.
https://codereview.chromium.org/860283004/diff/1/src/compiler/x64/instruction-selector-x64.cc
File src/compiler/x64/instruction-selector-x64.cc (right):
https://codereview.chromium.org/860283004/diff/1/src/compiler/x64/instruction-selector-x64.cc#newcode14
src/compiler/x64/instruction-selector-x64.cc:14: static bool
OpZeroExtends(Node *value) {
Use anonymous namespace instead of static.
https://codereview.chromium.org/860283004/diff/1/src/compiler/x64/instruction-selector-x64.cc#newcode132
src/compiler/x64/instruction-selector-x64.cc:132: if (index32->opcode()
== IrOpcode::kInt32Add) {
I don't think this optimization is sound. You basically assume that
ChangeUint32ToUint64(Int32Add(x,y)) is equivalent to
Int64Add(ChangeUint32ToUint64(x), ChangeUint32ToUint64(y)), which
doesn't hold in general.
https://codereview.chromium.org/860283004/diff/1/src/compiler/x64/instruction-selector-x64.cc#newcode134
src/compiler/x64/instruction-selector-x64.cc:134: if
(madd.right().HasValue() && OpZeroExtends(madd.left().node()) &&
CanBeImmediate(mdd.right().node()) implies madd.right().HasValue(), so
you don't need to check madd.right().HasValue().
https://codereview.chromium.org/860283004/
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